Re: Upgrade Suggestions.
2 more GBs will help, and i wouldnt worry about overclocking potential, as they are already 1066mhz. Just make sure they are the same model number and timings. I have 2 different sets of ram (both G.Skill HZs though) and one pair is better than the other...
It doesnt matter which 3870 brand you get, as long as it is the same speed as your one - it doesnt actually have to be the same speed, but it will downclock the faster one. 2x 3870s will probably perform around the same, maybe slighly better than a 4870. It should do a fair bit better than the 4850.